#include <stdio.h>
#include <string.h>
void reverse_string(char* str)
{
	int len = strlen(str);
	char temp = *str;//1
	*str = *(str + len - 1);//2
	*(str + len - 1) = '\0';//3
	if (strlen(str + 1) >= 2)

		reverse_string(str + 1);//4
	*(str + len - 1) = temp;//5


}

int main()
{
	char arr[] = "abcdef";
	reverse_string(arr);
	printf("%s\n", arr);
	return 0;
}